输电线路中频融冰频率与热功率均匀度分析

输电线路的覆冰会引发线路过负载、绝缘性能降低、杆塔倒塌、导线舞动等事故,而主流的短路融冰方法都存在着不可克服的缺陷;为此在高频激励新型输电线路融冰方法基础上,针对其在冰层介质损耗角正切值较小时电源频率过高的问题,提出了以牺牲一定融冰热功率均匀度为代价的中频融冰方法。首先基于均匀传输线理论,以长为100 km、电压等级为220 kV输电线路为例,搭建覆冰线路均匀传输线等效电路模型;继而分析沿线电压、电流和功率因数分布规律以及融冰频率与热功率均匀度的相互影响;最后提出输电线路中频融冰最佳电源频率的确定方法。仿真结果验证了所提方法的有效性与实用性。     

飞机防冰涂料的研究进展

介绍了防冰涂料的机理以及国内外防冰涂料的研究进展,包括低表面能、形成粗糙表面结构的超疏水涂层,同时分析了将防冰涂料与热除冰技术联合使用的可行性,讨论了防冰涂料应用存在的问题,对防冰涂料的发展趋势进行了分析和展望。     

基于高频高压激励法的输电线路融冰方法研究

针对现有输电线路融冰技术的缺陷,提出了一种基于线路集肤效应和电介质损耗理论的18kV、40 kHz高频高压激励融冰方法.该方法通过提高线路融冰电流的频率来加深线路的集肤效应,使线路单位长度的电阻显著提高,即在相同的发热功率要求下可减少线路的传输电流.简要论述了除冰装置的具体构成及其线路连接运行图.根据1000 kV特高...     

特高压直流输电系统换流站的优化设计(英文)

Based on the consultation and study for Xiangjiaba-Shanghai ±800 kV UHVDC(ultra high voltage direct current) project,this paper presents an optimal design for key technique solutions.In this paper,the DC system electrical scheme design,the DC filter design,the DC harmonic component suppression,the over voltage and insulation coordination,the requirements for converter station equipment,the main equipment technical parameters of equipment(including thyristor valve,converter transformer,smoothing reactor,DC breaker),the configuration of measuring device and DC control protection system,and the de-icing operation design are investigated.According to the UHVDC technology researched conclusions and the development of the project construction,the UHVDC system design for converter stations becomes an optimal combination.The optimized design solves numbers of technical problems of the world’s first UHVDC project,and it is applied to the project’s construction.Under the actual operating condition,the optimized design is proved to be correct and superior.These optimal design conclusions are impartment for developing UHVDC technique and equipment,and provide reference for future UHVDC projects.     

直流融冰及无功功率补偿系统研究

为进一步提升融冰装置性能,研究了兼备STATCOM动态无功功率补偿以及线路直流融冰功能的系统。该系统采用双链式STATCOM拓扑结构,采用动态无功电流跟踪技术以及中性点偏移的控制方式,实现动态无功功率支撑与线路直流融冰等双重功能。首先介绍了该直流融冰系统的结构,并详细研究了系统控制策略,根据系统应用的不同功能对其输出功率进行分析,同时搭建了基于EMTDC/PSCAD仿真模型对控制策略进行验证。最后,以12 MW直流融冰兼STATCOM系统为例制作了样机进行实验,论证了系统设计的可行性。     

基于文本规则的电网融冰决策技术

通过分析文本知识表达技术,重点介绍状态空间法、二值法和产生式系统。根据文本相关规定,对电网冰情制定了分级标准,对冰情的严重程度有了定量的衡量。通过提取文本元规则,选择控制策略,经过规则消除冲突,规则融合,得到1组新的规则集。在状态空间法的基础上,利用分级标准,结合二值法对规则集进行处理,得到1组能用数字和符号描述的规则集。在VFP软件平台上,根据规则集通过编程实现了不同类型电网融冰、除冰措施实施条件的决策。     

冰雪灾害条件下我国电网安全运行面临的问题

论述了防止复杂大电网发生冰灾事故的各个环节,介绍了研究现状和存在的问题,指出了在冰雪灾害条件下我国复杂大电网安全运行需要加强研究的8个关键问题：覆冰机理、覆冰外绝缘故障机理、有效的防冰、除冰方法、大电网覆冰在线监测与诊断方法、覆冰线路灾害局部化设计、电网覆冰在线评估、预警与决策以及建立复杂大电网覆冰灾害应急处理体系,并提出了可能的解决方法。     

不控整流型直流融冰装置设计与仿真研究

针对目前直流线路的直流融冰方法研究现状,提出了一种基于双24脉波不控整流器的直流融冰装置,可以通过改变整流变压器二次侧电压档位以及整流器输出连接方式来扩大装置融冰范围。给出了详细的直流融冰装置设计方案,在PSCAD/EMTDC仿真软件中搭建了直流融冰装置模型,仿真结果验证了设计的有效性。     

Corrosion behaviour of aircraft coating systems in acetate- and formate-based de-icing chemicals

Corrosion behaviour of four coating systems, which are commonly used in aircraft components; namely cadmium-coated and subsequently chromate-treated steel AISI 4340, aluminium-coated steel AISI 4340, anodised aluminium alloy 7075-T6 and chromate-treated aluminium alloy 7075-T6, were investigated in six commercial acetate- and formate-based de-icing chemicals. The results show that the aluminium-coated steel specimens experience least corrosion among the four coating systems; no corrosion is detected in potassium acetate-based de-icing chemicals (Safeway KA HOT, Safegrip and Safegrip+), although some corrosion is observed in the other three chemicals (Safeway SD, Safeway SF and Meltium). In contrast, the coatings in the other three coating systems are damaged in all six de-icing chemicals. The thickness of the coating does not necessarily predict how well the coating will protect the substrate; the thickest coating, several tens of micrometres, is apparent on the cadmium- and chromate-coated steel specimens, while only a few micrometres thin aluminium coating on the steel substrate is the only coating system that can survive the corrosion tests in some of the de-icing chemicals. Comparison of the results from the two test methods used in this research, polarisation measurements and chemical exposure tests, shows that, for each coating system, the extent of corrosion, as evaluated on the basis of weight changes calculated from corrosion current density values and those experienced during chemical exposure tests, is different: the weight changes that materialise during exposure tests are, at least, from one to two orders of magnitude higher than those predicted by calculations. In this paper, these observations are discussed and explanations for them are presented.     

贵州电网融冰方法的研究和应用

对2011年冰灾中贵州电网在110 kV及以下输电线路采取的融冰方法进行了总结,分析了各种方法的应用范围,比较其优缺点。基于贵州电网的实践,提出主要采用车载直流融冰装置和融冰变压器两种措施进行110 kV及以下输电线路融冰,并完成了相应样机的研制。现场试验证明了所提措施的可行性。